Repeating method and system



Patented Oct. 7, 1924.

UNITED STATES PATENT OFFICE.

ALEXANDER M. NICOLSON, OF NEW YORK, N. Y., ASSIGNOB TO ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION 01' NEW YORK.

BEPEATING METHOD AND SYSTEM.

Application filed March 18, 1918. Serial No. 223,221.

To all whom it may concern:

Be it known that I, ALEXANDER M. NICOL- soN, a subject of the King of Great Britain, residing at New York, in the county of New York, State of New York, have invented certain new and useful Improvements in Repeating Methods and Systems, of which the following is a full, clear, concise, and exact description.

The invention relates to repeating methods and systems in which weak impulses received at a repeating station are to be repeated and sent out upon the line in amplified form. Such a repeating system may-be inserted in a telephone line, for instance, for repeating telephone currents or ringing currents, and in this case it is necessary that the repeater transmit currents in opposite directions over the line to provide for the two-way transmission of si als.

A repeating element, suc as any vacuum tube repeater is inherently a unilateral conductor, and in order to provide for twoway repeating, it has been proposed to use either (a) two repeaters connected in opposition between the line sections, or (b) a single repeater which is reversibly connected between the line sections.

The first expedient is open to objection because the input of one repeater being connected to the output of the other, a useless, and in fact objectionable, circulation of power at the repeating station may take place, resulting in some instances in singing or howling, due to the generation of audible frequency currents. This objection has been previously overcome by various schemes which depend for their operation upon simulating or modifying the impedance of the telephone line. The scheme under (1)) is objectionable because of use of switch contacts which must'be opened and closed.

According to the present invention unilateral repeating devices are adapted for two-way repeating, in such a manner that none of the expedients noted under (a) and (b) above need be employed, a local circulatlon of power being revented without simulating or modifying the line impedance, and the repeater being permanently connected in circuit.

Use is made of vacuum tube repeaters and of the fact that such repeaters may be rendered inoperative by temporarily assigning a sufiiciently high ne ative potential to the control electrode 0 the repeater. This serves to reduce the space current within the vacuum tube substantially to zero. When the negative potential is removed from the electrode of the repeater the operative condition of the repeater is restored.

The invention provides two vacuum tube repeaters connected in opposition between the two line sections. A rectifying circuit is provided from the output side of each repeater to the input side of the other. The currents to be repeated coming in over one of the lines after passing through the corresponding repeater are rectified and applied to the other repeater, thereby rendermg the latter inoperative. The first repeater remains in an operative condition so that repeating may take place in the proper direction between the line sections. Upon the cessation of the current to be repeated, both re eaters assume their normal operative condition and either repeater is subsequently rendered inoperative by the currents coming in over the other line, so

that the two-way transmission of signals is provided.

For further details of the invention reference may be made to the drawings, in which the single figure shows one embodiment of the invention. 1

Referring to the drawings, between the line sections'l and 2 are provided the repeaters 3 and 4 of the audion type.

lines 1 and 2, the repeater 3 transmitting in a direction from line 1 to line 2, and repeater These repeaters are connected in opposition between 4: transmitting in the opposite direction' Current coming in over lme 1 impresses a potential, by means of the repeating 'coil 5, between the filament and the grid of the repeater 3. The output circuit of repeater 3 is coupled by means of repeating coil 6 to the line 2, so that weak impulses coming in over the line 1 may be amplified by repeater 3 and transferred to line 2. Similarly currents coming in over line 2, by means of the repeating coil 7, impress a potential between the grid and filament of the repeater 4, the output circuit of which is coupled by means of, repeating coil 8 to the line 1.

It will be seen that the currents coming in over line 1 will be amplified by repeater 3, transferred to the line 2, and, unless the special means which will later be described are provided, the amplified currents in line 2 will also be transferred back by means of repeating coil? to the repeater 4. Amphfied currents from the output circuit of reeater 4 would then be transferred to the inc 1 and to the repeater 3 as well. The repeaters 3 and 4 would reamplify the current an indefinite number of times, due to the fact that the two repeaters would be 0 eratively coupled together. This local circulation of power is objectionable, as previously described, and in order to prevent it the following means are provided. The output circuit of repeater 3 is provided with a repeating coil 9, by means of which some of the amplified currents are transferred to a rectifying circuit 10, which impresses the amplified and rectified currents between the filament and auxiliary electrode 11 of the repeater 4. The circuit 10 comprises 'a suitable rectifier, such as a vacuum tube rectifier 12 (as shown), and this rectifier is connected in circuit in such a way that the auxiliary electrode 11 is made negative with respect to its adjacent filament. The negative potential applied to the electrode 11 is sufiicient to reduce the space current within the repeater 4 to zero, thereby neutralizin or cancelling the eflect of the current :fe back from line 2 to repeater 4. This repeater is consequentl rendered inoperative, or its transmission e cienc is reduced while the repeater 3 is transmitting the current to be repeated. In order to release the nega tive charge of the auxiliary electrode 11 when current is no longer coming in over the line 1, the rectifier 12' is provided with a leakage path 13 in shunt thereto. This leakage path as shown contains an iron core inductance 14 which has a suflicient time lag to maintain the ne ative potential of the electrode in spite of fiuctuations of the incoming current. Upon a substantial interruption in the incoming current, the potential between the electrode 11 and its corresponding filament is equalized through the leakage path 13. The repeater 4 has coupled to its output circuit a rectifier 15, similar to 12, by means of which the rectified current may be applied to an auxiliary electrode 16, similar to electrode 11. It will be apparent that current coming in over either line will render one of the repeaters inoperative, so that the current in the outgoi line cannot be transmitted back through the repeating system, thereby preventing a local circulation of power.

Although only one embodiment of the invention has been shown it is apparent that many chan es may be made therein without departing from the spirit of the invention, and that the invention is not restricted to the type of rectifier or repeater shown or to any particular arrangement of the electrodes within the vacuum tube repeaters. While the invention discloses an arrangement in which the currents derived from each repeater are rectified before they are applied to the other repeater for rendering the same inoperative, it is obvious that the invention is not limited to this arrangement, as any other scheme may be employed, by means of which the currents derived from one repeater are applied to the other for renderlng the same inoperative. For instance, the currents in the rectifying or neutralizing circuit 10 maybe of the same wave form but opposite in phase to the currents to be repeated, as described and claimed in IE D. Johnson application, Serial No. 214,965,

filed Feb. 1, 1918, Repeater circuits.

What is claimed is: 1. The combination of two lines, two repeater paths oppositely and permanently connected therebetween, and impedance varyingmeans responsive to the current im- I pressed on said llnes for reducing the transmission efliciency of one of said paths.

2. A two-way repeater system comprising two lines, two repeater paths oppositely and permanently connected therebetween, each path comprising an electron discharge tube, and means responsive to-current impressed on said lines for changing the impedance of one of said tubes when the other tube is operative.

3. A two-way repeater system comprising. two lines, two vacuum tube repeater paths oppositely connected therebetween, and means responsive to the current impressed on the said lines for supplying a negative potential to an electrode within a tube in each of said paths for rendering one of said paths inoperative when the other is operative.

4. The combination of a vacuum tube repeater comprising input electrodes, means for supplying to said electrodes waves to be transmitted to a distance, and means effective continuously while said waves are received by said input electrodes for rendering said repeater inoperative to repeat the waves received by said input electrodes.

5. The combination of two lines, two repeaters of the audion type having input electrodes, said repeaters being connected between said lines, and a transmission emciency controlling connection between said repeaters independent od 'said lines, for opposing the efi'ect of waves received by one of said repeaters. 6. A signaling station comprising a transmitting channel, a receiving channel, and

impedance varying means responsive to current transmitted in said transm ttin channel for so reducing the transmlssion efficiency of said receiving channel as to block transmission in said receiving channel while the circuit continuity of said receiving channel is maintained.

.7. A two-way repeating system comprising two lines, two vacuum tube repeater pgths pointing in opposite directions there- 1 tween, said vacuum tubes having electrodes therein and means responsive to the current impressed on said lines for suppl ing a negative potential to an electro e within one or the other of said tubes while both positive and negative half waves of the incoming current are being repeated.

8. A two-wa repeating system comprising vacuum tu e repeaters pointing in opposite directions, a connection from the output side of each repeater to the other repeater, and a rectifier in each of said connections for energizing said other repeater.

9. A vacuum tube repeater and means comprising a rectifier for energing said repeater to render it substantially inoperative.

10. A vacuum tube repeater, an electrode therefor, a rectifier, and connections between said electrode and saidrectifier for energizing said electrode to render said repeater" substantially inoperative.

11. A two-way repeating system comprising vacuum tube repeaters pointing in opposite directions, a connection from the output side of each repeater to the other repeater, and rectifying means responsive to the waves to be. repeated for energizing either of said repeaters to render it inoperative while the other is repeating.

12. A repeating system comprising a line, two-way repeating means therefor, and thermionic means responsive to the current impressed on said line for energizing said repeating means for preventing a local circulation of power through said repeating meansindependently of the impedance of said line.

13. A two-way repeating system comprising two lines, two vacuum tube repeaters pointing in o posite directions between said lines, means or supplying space current for said tubes, and means responsive to the current impressed on said lines for reducing substantially to zero the space current within said tubes.

14. A system for transmitting waves substantially without distortion comprising the combination of a line, a repeater therefor, and means comprising a rectifier for energizing said repeater for controlling the efficiency of said repeater.

15. A system for transmitting waves substantially without distortion comprising the combination of a line, a repeater therefor, and means, comprising a rectifier adapted to be energized by the waves to be repeated, for energizing said repeater for controlling the efliciencyof said repeater.

16. A system for transmitting waves substantially without distortion comprising the combination of a line, an amplifier therefor, a circuit for transmitting the amplified waves, a rectifier, a circuit between said rectifier and the out ut side of said amplifier, a second ampli ler, and an energizmg connection between said rectifier and said second amplifier.

17. The combination of an incoming and an outgoing line, a vacuum tube repeater therebetween, and means for controlling said repeater comprising a rectifier, an inductive leak ath therefor and a circuit connecting sai rectifier to said repeater.

18. In a telephone system, means for transmitting currents of voice frequency, a unilateral conductor and a path in shunt to said conductor and effectively connected to said means, said path transmitting current in the opposite direction from that transmitted by said unilateral conductor.

19. A source of current, a unilateral conductor and a reactive path in shunt thereto and energized by said source, and a thermionic device ada ted to be ener 'zed by current through sald unilateral con uctor.

20. In a telephone system the combination of means for transmitting currents of voice frequency, a rectifier in series therewith, and a leak path in shunt to said rectifier.

21. The combination with a vacuum tube, 109 of means for transmitting voice frequency waves thereto, a rectifier, a circuit connecting said rectifier with said vacuum tube,

and an inductive leak path for said rectifier.

22, In a signaling system, the combination of means for transmitting currents of voice frequency, a rectifier in circuit therewith and an inductance in shunt to said rectifier.

23. Ina signaling system, the combination of means for transmitting currents of voice frequency, a rectifier in circuit therewith, an inductance in shunt to said rectifier, and. an iron core for said inductance.

24. A two-way repeating system compris- 11 ing two line sections, two oppositely connected audion repeater paths therebetween, and a rectifier path from each of said repeater paths to the other repeater path for energizlng the repeater in said other path.

25. The combination of an incoming and an outgoing line, a vacuum tube repeater therebetween, and means for controlling said repeater comprising a rectifier con-, nected to supply voltage thereto and a leak 12E path for said rectifier.

26. The combination with electrodes of a vacuum tube, of means for supplying voice frequency waves thereto, a rectifier for supplying voltage to said vacuum tube, said rectifier being connected in circuit with said means, and a leak path for said rectifier.

27. The method of controlling a unidirectional repeater connected in a line which 5 comprises supplying waves to the input terminals of said repeater over said line from the direction toward which said repeater points and rendering said repeater inoperraroeee ative to repeat Waves in response to said Waves reeching said input terminals from it said direction.

In witness whereof, I hereunto subscribe my1 name this 12th day of March A. D, 19 8.

ALEXANDER M. NrcorisoN. 

